Gamma globulin is widely used as a therapeutic agent, and generally, it is administrated by intramuscular injection. Impurities, such as aggregates of gamma globulin occasionally contained in gamma globulin products, render hazardous the administration of such gamma globulin products by intravenous injection.
Accordingly, for the purpose of preparing gamma globulin composition free of aggregates thereof, there have been proposed methods of preparing gamma globulin under such conditions that aggregates are not produced. There have also been proposed methods of removing any aggregates that are produced in the course of preparing the gamma globulin, which removal takes place at the last step of the procedure. Such methods for the production or purification of gamma globulin have been disclosed in the literature, for instance, U.S. Pat. Nos. 3,415,804, 3,763,135, 4,093,606 and 4,124,576, and British Pat. No. 1 372 953.
In the methods disclosed in these patents, polyethylene glycol is used for the purpose of production or purification of gamma globulin.
It is an object of this invention to provide a method of preparing gamma globulin, not containing aggregates of gamma globulin, by using polypropylene glycol(PPG).
The inventors have found that gamma globulin products not containing aggregates of gamma globulin can be obtained by treating a gamma globulin composition with PPG under selected conditions as described in the following. In the invention process, the gamma globulin aggregates can be removed, and gamma globulin products suitable for intravenous administration can be obtained from a crude gamma globulin composition, which products do not contain gamma globulin aggregates and have a low anti-complementary activity (ACA). This invention is based on this discovery.